Well, I'm not real experienced in knowing whats viable, I have a really good flashlight and candling is pretty easy...of the 40 eggs total, 4-5 were clear, there was something going on in all the others....I haven't candled in about a week.....looking at the calendar, you are correct tomorrow...duh, the red dorks a day later.....
I am no great candler, I just look for a dark area and a solid air cell....beyond that I just don't worry much about it. I pull clears and sloshy eggs on day 10 so the broody doesn't need to bother with them but that is about it.